Circuit interrupter



March 20,1951 H. w. GRAYBILL 2,545,660

CIRCUI'T- INTERRUPTER Filed Nov. 25, 1945 WITNESSES: INVENTOR Howard 14/ Grayfiz'll.

mm 6f4 Patented Mar. 20, 1951 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTER Howard W. Graybill, Honey Brook, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 23, 1945, Serial No. 630,430

10 Claims.

This invention relates generally to electric' .Open an electric circuit in response to the presence in the circuit of excessive currents.

Another object of this invention is to provide an electric circuit opening device with novel latch release means for a movable contact member which is biased to move to open the circuit when released.

Another object of this invention is to provide a circuit protective device having means responsive to excess currents for switching the circuit to ground; with novel means for extinguishing the are drawn during such switching operation.

Another object of this invention is to provide .a circuit protective device which is automatically operative to ground the circuit in response to excess currents, with surge protective means which cooperates therewith to extinguish the are drawn when the device operates in response to excess currents.

These and other objects of this invention will become more apparent on consideration of the following detailed description of a preferred embodiment thereof and the attached drawing, in

which: n v

Figure l is a side elevational view of a device embodying this invention; c

Fig. 2 is a front view of the circuit protective device illustrated in Fig. 1; and

Fig. 3 is an enlarged sectional view of the in- 5. The ends of insulator 2 are also reduced in section for receiving terminal brackets 4 and 6,

respectively, adapted tobe secured thereon as by 5'' Although a single insulator clamping bolts 8. mounting is illustrated, it will be obvious to those skilled in the art that terminal brackets 4 and 6 may be mounted on separate insulators, if desired.

, Upperterminal bracket 4 has secured thereto .3 terrupter contact structure of the device shown an angular contact bracket ID, for example, as I by bolts l2. Contact bracket 10 has a forwardly extending contact arm I4 with 'a'n elongated cen: trally located narrow slot [6 extending inwardly from the outer end thereof. A casing l8, prererably of a molded insulating material, such as a synthetic resin, having an open bottom and a peripheral flange around the lower edge thereof is adapted to be secured to contact arm 14 as by bolts [9 extending through the contact arm and bottom flange of the casing. At the forward end of casing !8 there is provided a substantially U- shaped terminal rod 2!, with one leg being threaded and extending through an aperture in the top of casing l8 and secured relative to the casing by nuts 22 and 23. A pair of nuts 22 is provided at the top of the casing for securing one conductor of the circuit to terminal rod 2|. Within casing l3, leg 26 of terminal rod 2| extends through an aperture in a bimetal element 24, which may be secured in adjusted position on the rod as by nuts 26. The bight portion 30 of the terminal rod extends through a notch 28 formed in th forward lower edge or casing I8, and leg 32 of the terminal rod extends upwardly in front of the casing, and has an angularly directed outer arcing horn portion 34, for a purpose to be described. An angular arc bracket 36 may be secured to leg 32 of terminal rod 2| as by a securing plate 38 secured to bracket 36 as by bolts 40, with leg 32 of the terminal rod held therebetween. Arcing bracket 36 has a rearwardly extending part 42 secured to the lower flange of housing I8 as by bolts 44, and it terminates short of the forward end of contact arm I 4 to leave a space 46 therebetween.

Bimetal element 24 is formed in the usual manner of a pair of laminations 41 and 49 secured together in intimate relation, as by welding or the like, with the lamination 41 being of a metal such as steel having a relatively low coefficient of thermal expansion, whereas lamination 49 is of a metal such as brass having a relatively high coefiicient of thermal expansion. It will be observed, therefore, that when bimetal element 24 is heated, the outer end will deflect upwardly as viewed in Fig.3. The outer end of bimetal element 24 has an abutment 48 secured thereto as by a rivet 50, and the outer end of the bimetal element is electrically connected with contact arm 14 of bracket m by a flexible conductor 52 soldered or otherwise secured at its ends to contact arm l4 and bimetal element 24, respectively. Abutment 48 on the bimetal element is adapted to cooperate with one end of a latch lever 54 which is pivotally mounted intermediate its ends on contact arm 14 as at 5B. A light coil tension spring 58 has one end hooked in an opening provided in latch lever 54, and the other end hooked over an anchor lug 60 secured to the contact arm 14 to bias the which is shown) latch lever to a position slightly clockwise from that shown in Fig. 3, so that the upper end of the lever will normally be in a position to be engaged by abutment 48 of the bimetal element.

The lower end of latch lever 54 is adapted, at the closed circuit position, to be engaged by a contact arcing tip 62 secured to the outer end of a switch member 64 which is 'pivotally mounted at its other end on terminal bracket 6, as at 11. Switch member 64 is preferably of a resilient con-- ducting material, and in the device illustrated in the drawing comprises a pair of resilient rods 66 and 68 having the inner ends thereof bent towards each other to enter openings in opposite sides of terminal bracket 6 to be pivotally mounted at ll, and a coil spring 69 reacts between extension of rod 68 and bolt 8 to bias switch member 64 in a clockwise direction, as viewed in Fig. 1, to open circuit position. Rod 68 of the switch member has the inner extension 16 adapted to limit circuit opening movement of the switch member by engagement with the lower end of insulator 2 after predetermined opening movement. The outer ends of rods 66 and 68 of switch member 64 are each bent to form a loop 12 at substantially the same position so that the loops 12 form a hookeye for receiving a hookstick operating member, for operation of switch member 64 in a manner to be described. It will be observed that rods 66 and 68 of switch member 64 are subsantially U-shaped in profile, so that in the closed circuit position contact tip 62, which is secured across the outer ends of rods 66 and 68 as by welding or the like, engages contact arm l4 under pressure due to the fact that the ends of the switch member are s'.ressed toward each other a certain amount, and for this purpose loops 12 act to increase the flexibility of the-switch arm.

To provide surge protection and to extinguish arcs drawn during circuit opening movement of 1 switch member 64, there is provided a rod 14 of electrical conducting material having its inner end mounted on an extension 16 of mounting bracket 3, for example, as by being threaded and secured to extension 16 by nuts 18 (only one of Rod 14 includes a forwardly extending portion 80, at the end of which is an angularly bent upright poriion 82 which extends upwardly to theregion of terminal bracket 4 and a then a transversel extending part 84 extends to a point in opposition to arcing bracket 36, and the rod terminates in an angularly ex Lendingarcing horn part 86 which diverges with respect to arcing horn 32. Substantially at the bend 85 between parts 84 and 86 of rod 14, the rod lies closest to arcing bracket 36 so that these two members form electrodes for a surge gap.

Arcing horn 86 is grounded, for example, as by grounding supporting bracket 3 as illustrated in Fig. l, and it will be observed that the normal current flow through the device illustrated at the closed circuit position thereof is from terminal rod 2| through bimetal element 24, flexible conductor 52, contact arm l4, contact tip 62, through switch member 64 to terminal bracket 6 anda terminal 88 secured thereto. When currents above a predetermined value flow through this circuit, bimetal element 24 will be heated, and the outer end will deflect upwardly to release the upper end of latch lever 54. When latch lever 54 is released from abutment 48, it can then be rotated counterclockwise by switch member 64 under the influence of its biasing spring 69, and the switch member can move to open circuit po- 4 sition. As soon as contact tip 62 goes past the lower end of latch lever 54, the latch lever will be returned to a position slightly clockwise from the position shown in Fig. 3 by return spring 58. As contact tip 62 slides over the lower surface of contact arm I4 and onto the lower surface of arm 52 of the arcing bracket, the bimetal element is shunted out of the circuit because the circuit then proceeds from terminal rod 2| through arcing bracket 36, contact tip 62 and switch member 64 to the lower terminal 68.

As contact tip 62 continues to move to the right, as viewed in Figs. 1 and 2, it will leave arcing bracket 36, and an arc will be drawn between tip 62 and the arcing bracket, and as soon as contact tip 62 passes immediately under electrode portion of the grounded rod 14, the arc will be transferred from arcing tip 62 to rod 14, where it will be subjected to the arc extinguishing action of horns 32 and 86, namely, the arc will be elongated by travel upwardly on the horns and by looping outwardly, due'to the magnetic forces present. Travel of switch member 64 is stopped just beyond electrode portion 85, as illustrated by the partial dotted line position shown at Fig. 1, by engagement of extension T0 with the lower end of insulator 2, as previously described. Currents of appreciable value may be extinguished upon automatic opening of the" device, as described above, due to the arc extinguishing action of arc horns 32 and 86, However, it may be desirable where extremel heavy shortcircuit currents are encountered to provide a circuit breaker or the like connected in the same circuit, to open the circuit on such heavy shortcircuit curren-s in case the arc extinguishing action of the arcing horns is insufiicient to extinguish such currents.

After an automatic circuit opening operation as described above, the interrupter may be closed by inserting a- .hookstick, or other operating member, in hookeyes 72 and moving switch member 64 in a counterclockwise direction from the dotted line position shown in Fig. 1 back toward the full line position. The circuit is reestablished when arcing tip 62 engages arcing bracket 36, and such engagement causes the outer end of switch member 64 to be bent downward to stress the switch member, and thus cause the arcing tip to engage part 42 of the arcing bracket under pressure, and finally to engage contact arm I4 in a similar manner, and eventually "the arcing tip engages latch lever 54- rotating it in a clock-- wise direction while. assing by, and when the latch lever is restored by its spring 58, the contact tip will engage the other side of the latch lever and hold it in engagement with abutment 48 on the bimetal element. The circuit may be opened manually, if desired, by inserting a hook stick or the like in hook'eyes 12 andpulling downwardly to spring the outer end of switch mein ber 64 downwardly below the lower end of latch lever 52, after which the switch member may be rotated-in clockwise direction to its open position either manually, or by its biasing spring 69 The gap between archorns 32 and 86 should be adjusted to coordinate with the insulation of the apparatus, such as a transformer or the like, which is being protected, so thatsurge voltages above the safe value of such insulation will break down the gap, to form an are on the arc horns which will be extinguished in the manner described above. If the power follow current isof exceptionally high value, or if this apparatus is to be mounted below other conductors or ground ed 'parts, it may be desirable to depend u on a reclosing circuit breaker, or the like, connected in the circuit for interrupting the circuit to extinguish such arc. However, the arc extinguishing ability of arcing horns 32 and 86 will operate to' extinguish overload currents of substantial value.

From the foregoing it is believed apparent that this invention provides a novel electric circuit protective device capable of protecting the circuit and apparatus therein from overloads and surges, and that by a novel cooperation of parts, arcs due to both surges and overloads are caused to form between the same pair of electrodes, and are subjected to the same arc extinguishing action.

"There is also disclosed herein a circuit protective device having a novel switch member construction, together with novel latch means, for-nor- 'mally holding the switch member closed and adapted to be automatically released in response 'asmuch as it will be obvious to persons skilled in this art that many changes and modifications may be made therein without departing from the broad spirit and scope of this invention. For example, it has already been pointed out that in- .stead of having a single insulator mounting that spaced insulators may be used, and these may be 'Smounted on a channel support or the like which is grounded and also supports arcing horn rod- .30. Accordingly, it is desired that this invention .be. interpreted as broadly as possible, and that it be" restricted only as required by the prior art.

I claim as my invention:

1. A circuit protective device, comprising, separable line contacts one of which is mounted for movement into and out of engagement with the other, grounded terminal means having a terminal portion supported adjacent to but spaced from said other contact to form a low resistance surge gap to ground and which is of a length correlated to protect the circuit insulation, and said gap extending adjacent to and in the directionof movement of said movable contact so that thearc drawn upon separatin movement of said movable contact will transfer to the terminals of said surge gap.

2. A circuit protective device, comprising, separable line contacts one of which is mounted for movement into and out of engagement with the other, grounded terminal means having a terminal portion supported adjacent to but spaced from said other contact to form a low resistance surge gap to ground and which is of a length correlated to protect the circuit insulation, and means to transfer the are drawn during circuit opening movement of said movable contact to the terminals of said surge gap.

3. A circuit protective device, comprising, separable line contacts one of which is mounted for movement into and out of engagement with the other, grounded terminal means having a terminal portion supported adjacent to but spaced from said other contact to form a low resistance surge gap to ground and which is of a length correlated to protect the circuit insulation, means to transfer the are drawn during circuit opening movement of said movable contact to the terminals of said surge gap, and means for extinguishing an are formed across said gap.

4. A circuit protective device, com rising, separable line contacts one of which is mounted for movement into and out of engagement with the othengrounded terminal means having a terminal portion supported adjacent to but spaced from said other contact to form a low resistance surge gap to ground and which is of a lengthcorrelated to protect the circuit insulation, said gap extending adjacent to and in the direction of movement of said movable contact so that the are drawn upon separating movement of said movable contact will betransferred to the terminals of said surge gap, and means for extinguishing an arc formed across said gap.

5. A circuit protective device, compris-ng, separable line contacts one of which is mounted for movement into and out of engagement with the other, a line terminal electrically connected with each of said contacts, latch means for normally holding said movable contact in engagement with said other contact including means in the connection of said other contact and its terminal which is responsive to a predetermined condition of the circuit to release said latch means, a stationary arcing electrode independently connected with the terminal of said other contact and positioned adjacent the path of circuit opening movement of said movable contact, a ground electrode spaced from said arcing electrode to form a low resistance surge gap to ground and which is o f a length correlated to protect the circuit insulation, and saidgap extending adjacent to and in the direction of movement of said movable contact so that the are drawn upon separating movement of said movable contact will be transferred to the terminals of said surge gap.

6. A circuit protective device, comprising, separable line contacts one of which is mounted for movement into and out of engagement with the other, a line terminal electrically connected with each of said contacts, latch means for normally holding said movable contact in engagement with said other contact including means in the connection of said other contact and its terminal which is responsive to a predetermined condition of the circuit to release said latch means, a stationary arcin electrode independently connected with the terminal of said other contact and positioned adjacent the path of circuit opening movement of said movable contact, a ground electrode spaced from said arcing electrode to form a low resistance surge gap to ground and which is of a length correlated to protect the circuit insulation, said gap extending adjacent to and in the direction of movement of said movable contact so that the arc drawn upon separating movement of said movable contact will be transferred to the terminals of said surge gap, and means for extinguishing an are formed across said gap.

7. A circuit protective device, comprising, separable line contacts one of which is mounted for movement into and out of engagement with the other, spaced electrodes one of which is grounded and the other of which is electrically connected to one of said contacts to form a low resistance surge gap to ground and which is of a length correlated to protect th circuit insulation, and said gap extending adjacent to and in the direction of movement of said movable contact so that the arc drawn upon separating movement of said movable contact will be transferred to the terminals of said surge gap.

8. A circuit protective device, comprising, separable line contacts one of which is mounted for pivotal movement into and out of engagement someone 7 wit the other, ta i ine termina peleot t eall' no inenteidvzwz c ,achiof said ntaclts lateh iorhnormailly holdin :said m vable eontnctzin en a ement with said other ontac n ludin :means in the connection ,oinseid other contg t and its terminal 'wh'ionis responsive 2 L31 tuned? termined condition of the, ciroui-til fi irel a e saain iatoh .ameans, istationa-r arcing ele trode inglemendentlymconnected zWith the terminal of said oth r contact and positioned adjac nt the path ofoircuit openingmovement-of:send movablecon- -.itaot,-:-.a ground electrodes-spaced from said arcing :-.;e1ec,trogle to form ,a low resistance ,surgegapaio 'pmiiectaithe circuit insulation, :said al? extending -;adjacent tto. and :inthe direction-of movement of 'gsaiidimovahlecontact so thatithe arcidraivn upon :SeDamatingu-movementof said rmoizablelcontaqtwill ilaeitnansfenred :to:;t he terminals of said r unge gap,

and saidimovableiline cont-act 'bfiillgzflf qesilient "material "bent so as @170 engage ;the iother Aline 5contactnand ai ci-ngelectrode under pressure.

9. A=circuit=protective device,.coniprising, Separable line contacts .one of :WhiChiS mQUDiEGd for movement into and out of engagement with-. the other, -aline terminal electrically connected; with each of :said contacts, cilantro-responsivemeans for oausing separation oflsaid contacts and non- -=nected=intheeircuitbetween said other contact and its terminal, a stationary ia rcing ielectrode independently :connected vwith the ,itermingl; of said other contact and ,positioned fidjacentnthe path OfCiI"Cuit opening movement of :said mova- -b1e' contact, a'groundelgectrode spaced (from :said

arcing electrode to form a low resistance surge gap to ground and-which sis=of.a length corre- "lated to protect the circuit insulation, and. ,said -gap extending ad'jacentto andin,the diitection of movement of :said movable icontact so. that :the

en: drawnunqn s paratin mo ement vo said :ino entect w l ,b t an fi rre to thestenn r e ap- .iD- NA 9 qui pro ect ve s pfi 1 0 1111 ic pneai edsup rit ng insu ator. 1 1. 5 rte mounted-e ema insu at r zadiacen opnoswe nds thereof, supporting means mounted on said in retnnin ntmedia intior sunpo tie no o g ounded strii tn te 11 1c stipnairy'andimomhl icontacw mo."

' ins eqt ve y rf r efi more lnals o seidgsure t e .HQW -E GRAXEILL- BEEEB G TED The following references are of record ,in the :file .of -:this. patent:

IJNITED .STATES PATENTS 

